Nature Quest: Are Summers Getting Hotter?

Summary

Short Wave Podcast Summary Episode: Nature Quest: Are Summers Getting Hotter?
Release Date: July 29, 2025

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Listener's Perspective: Dwayne Stillwell's Experience

The episode begins with a heartfelt introduction of the listener question from Dwayne Stillwell, a 68-year-old who has experienced diverse climates throughout his life. Having lived in cities like Cleveland, Chicago, and New York City, and worked in varied environments—from the lush summers of Mexico City to the frigid Midwest—the recent years in Guadalupe, Arizona, were expected to be his permanent, comfortable retirement home. However, Dwayne's experience has dramatically shifted due to escalating summer heat.

Dwayne Stillwell (00:37): "I lived in Cleveland, in Chicago, New York City."

Emily Kwong and Hannah Chin set the stage by highlighting Dwayne's growing concerns as Guadalupe faces longer, hotter, and more perilous summers. Last year alone, Dwayne reported 113 consecutive days exceeding 100°F. The extreme heat led to the cessation of fruit production in his fig trees, the death of cacti in his yard, and tragically, the loss of his neighbor to heatstroke.

Dwayne Stillwell (01:28): "Be the last place I'd have to move, and I'm tired of moving, you know?"

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The Science Behind Rising Temperatures

Delving into the scientific underpinnings, the hosts explain the physics contributing to the increasing global temperatures. Climate scientist Justin Mankin from Dartmouth elucidates the concept of greenhouse gases, emphasizing that while water vapor is a natural greenhouse gas, anthropogenic emissions of carbon dioxide, methane, and nitrous oxide have significantly disrupted Earth's radiative balance.

Justin Mankin (05:09): "Greenhouse gas is just a term that scientists use to describe any gas in Earth's atmosphere that traps heat."

The metaphor of Earth's atmosphere as a "bathtub" effectively conveys how human activities are "clogging the drain" by adding excessive greenhouse gases, leading to sustained warming.

Emily Kwong (05:41): "Just as the water level in a bathtub fills up to push water down a clogged drain, so too, does the Earth warm."

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Impacts of Extreme Heat on Communities

The conversation transitions to the tangible effects of prolonged heatwaves. Since 1980, the average number of heatwaves in the U.S. has doubled, with the duration extending from 40 to 70 days. Elevated humidity exacerbates the situation by impairing the body’s ability to cool itself through sweat evaporation, increasing the risks of heat exhaustion and heatstroke.

Hannah Chin (06:56): "When the humidity is worse, our bodies are less efficient at evaporating sweat. And then if our sweat doesn't evaporate, our systems literally can't cool down."

Geographic location emerges as a critical factor in determining individual experiences of extreme heat, with urban areas suffering from the "urban heat island effect." This phenomenon disproportionately affects marginalized communities due to limited green spaces.

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Adaptation Strategies: Greening Urban Landscapes

To combat the urban heat island effect, the podcast highlights adaptive measures such as expanding parks, creating community gardens, and installing green roofs. Dwayne Stillwell explains the cooling mechanism of vegetation through transpiration, which effectively reduces surface temperatures.

Dwayne Stillwell (07:52): "Vegetation siphons water from below the land surface and sends it to the atmosphere through transpiration, which is a form of evaporation."

These green initiatives not only mitigate heat but also enhance the overall quality of urban environments.

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Public Health Initiatives: Cooling Centers

Addressing the immediate dangers of extreme heat, the episode discusses the implementation of cooling centers—air-conditioned public or private spaces designed to provide refuge during heatwaves. Nick Staub, Incident Commander for Extreme Heat Response in Maricopa County, Arizona, shares insights into the effectiveness of these centers.

Nick Staub (08:47): "Those who are at highest risk in our community are those who are unsheltered, those who are spending their nights out on the street."

In 2024, Maricopa County reported a decline in heat-related deaths, attributing this success to the expanded heat relief network that includes extended operation hours for cooling centers and the establishment of respite centers for temporary relief.

Nick Staub (10:16): "Down, but we still had over 600 heat related deaths in 2024. So while we are encouraged by the reversal of the trajectory, there is still a lot of work to be done."

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Early Warning Systems: Enhancing Preparedness

The National Weather Service plays a pivotal role in forecasting and issuing heat advisories through tools like the heat index, which combines air temperature and relative humidity to reflect perceived heat.

Emily Kwong (11:22): "The heat index is a measure of how hot it feels to the human body when relative humidity is combined with air temperature."

However, challenges remain, such as the heat index's calibration for shady areas, which doesn't account for the additional heat exposure in direct sunlight. This limitation underscores the importance of proactive planning beyond relying solely on official advisories.

Nick Staub (12:37): "You need to plan all summer long."

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Individual Actions and Mitigation Efforts

Listeners are encouraged to take personal and community-driven actions to mitigate the impacts of extreme heat. Practical advice includes:

• Alter Outdoor Activities: Schedule outdoor tasks during cooler parts of the day.
• Enhance Home Cooling: Use dark curtains and take cold showers to reduce indoor temperatures.
• Community Support: Regularly check on vulnerable friends, family, and neighbors.

Nick Staub (13:09): "Plan your outdoor activities wisely. Don't be outside during the heat of the day."

However, the hosts acknowledge that individual efforts, while beneficial, are insufficient without systemic changes to address the root causes of climate change.

Justin Mankin (13:36): "Ultimately it is fossil fuel emissions that are the root of the problem."

Dwayne Stillwell emphasizes the necessity of reducing greenhouse gas emissions to prevent further warming and extreme heat risks, highlighting that existing policies, if properly implemented, could effectively address the issue.

Dwayne Stillwell (13:42): "Mitigating our greenhouse gas emissions is going to be the clearest way to prevent additional warming and extreme heat risks, and we have the tools to do it."

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Conclusion: A Call to Action

The episode concludes with a strong message advocating for both individual preparedness and collective action to combat the escalating threat of extreme heat due to climate change. The hosts thank contributors and encourage listeners to engage with future episodes by submitting their environmental questions.

Emily Kwong (14:09): "Thank you Duane, for the great question."

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Credits and Acknowledgements

The episode was produced by Hannah Chin and Rachel Carlson, with editing by Rebecca Ramirez and contributions from Tyler Jones (fact-checking), Jimmy Keeley (audio engineering), Beth Donovan (senior director), and Colin Campbell (senior VP of podcasting strategy). Special thanks were extended to the National Weather Service and NPR's Climate Desk contributors Alejandra Burunda and Julia Simon.

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For more episodes and to support the show, visit Short Wave Plus.

Transcript

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[Emily Kwong]

You're listening to Short Wave from npr. Hey, everyone, Emily Kwong here with producer Hannah Chin, who is bringing us this month's listener question for Nature Quest, my favorite series ever. Okay, Hannah, who's the question coming from?

[Hannah Chin]

This question comes from Dwayne Stillwell. He's 68, and he's lived a lot of different lives in a lot of different places.

[Dwayne Stillwell]

I lived in Cleveland, in Chicago, New York City.

[Hannah Chin]

Dwayne grew up working summers as a delivery boy in the lush green of Mexico City. He taught chemistry in the dry heat of California, and he even worked as a railway switchman, tamping down in below freezing temperatures in the Midwest. Basically, he is no stranger to extreme weather. And when he retired and moved to the American Southwest five years ago, he kind of thought he was there to stay, that Guadalupe, Arizona, just outside of Phoenix, was his forever home.

[Emily Kwong]

I pretty much thought this was gonna.

[Dwayne Stillwell]

Be the last place I'd have to.

[Hannah Chin]

Move, and I'm tired of moving, you know?

[Emily Kwong]

Yeah, I feel that he's lived a lot of places. He's ready to settle, but now he's.

[Hannah Chin]

Not so sure because. Emily, over the past four years, the summers where Duane lives have become longer and hotter and more dangerous. Last year, Duane said there were 113 days in a row above 100 degrees Fahrenheit. His fig trees stopped producing fruit. Some of the cacti in his yard started dying. And his neighbor, who slept, an older guy who lives across the road with his family, passed from heatstroke.

[Emily Kwong]

It's forbiddingly hot. In other words, you know that if.

[Dwayne Stillwell]

You stay outside, you can die.

[Emily Kwong]

Since 1980, the average number of heat waves in the US has doubled, and the length of an average heat wave season has increased from 40 days to 70. We are facing a future with more summers like this. So this month's Nature Quest, Extreme heat, how it's linked to climate change, why humidity makes it worse and more deadly.

[Hannah Chin]

And how you heatproof your life for the future.

[Emily Kwong]

You're listening to Short Wave from npr.

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[Hannah Chin]

Okay. Short waivers. We are on a nature quest. This is our monthly segment that brings you a question from a fellow short waiver who is paying attention to the environment around them and the ways that it's changing. And this month, Emily Kwong is looking into extreme heat.

[Emily Kwong]

Yeah. I want to take you back to the summer of 2022 when Covid restrictions started to loosen and that Kate Bush song running up that Hill was everywhere.

[Hannah Chin]

I love an 80s bop, right?

[Emily Kwong]

I remember listening to that song thinking, this is so good. And also this 80s synth will not save me.

[Hannah Chin]

It is just too hot. I. I have to go inside. Yeah. I mean, it was that same summer that I think heat records were breaking around the world in Europe and in China. I even remember the US Secretary of Commerce at the time, Gina Raimondo, she said that this summer is likely to be one of the coolest summers of the rest of our lives.

[Emily Kwong]

Yeah. Hot as it was. So I want to talk about the physics of why this is happening and why the Earth, which does have natural variations in temperature, cannot simply correct for this much warming.

[Dwayne Stillwell]

As my PhD advisor would say, if you believe in thermometers, you believe in global warming. It is an observation of what is occurring.

[Emily Kwong]

This is Justin Mankin. He's a climate scientist and professor of geography at Dartmouth. And he reminded me that greenhouse gas is just a term that scientists use to describe any gas in Earth's atmosphere that traps heat. So water vapor is a greenhouse gas?

[Hannah Chin]

Oh, I didn't know that.

[Emily Kwong]

Yeah. But the gases that have been on the rise since the Industrial Revolution because of humans emitting fossil fuels, the gases we're all so worried about are carbon dioxide, methane, and nitrous oxide. You can think of our atmosphere almost like a bathtub. It gets full and typically Earth's Forests and oceans and soil act like a drain. They sequester carbon. In the long term, bring our planet back into equilibrium. The bathtub empties. But because human activity is emitting more greenhouse gases, the drain is getting clogged.

[Hannah Chin]

Oh, so the bathtub, like our atmosphere, is filling up.

[Emily Kwong]

Yeah. Just as the water level in a bathtub fills up to push water down a clogged drain, so too, does the Earth warm.

[Dwayne Stillwell]

The planet needs to heat up to ensure that the amount of energy we're receiving from the sun is balanced by the amount of energy Earth is sending out to space.

[Emily Kwong]

Justin says this is called radiative balance.

[Hannah Chin]

Radiative what?

[Emily Kwong]

It's kind of how the Earth and sun do what they do, and it's governed by the unchanging laws of physics. So one law says that all matter that has a temperature radiates energy. The sun, which is very hot, radiates energy. The Earth absorbs that energy and heats up, too. And another law of physics says that hotter objects will emit more energy, essentially shed that energy to achieve radiative balance.

[Hannah Chin]

Okay, so the Earth has to shed its heat.

[Emily Kwong]

Yes. And that's because of the law of the conservation of energy.

[Hannah Chin]

Right.

[Emily Kwong]

Energy cannot be created or destroyed. What goes in has to equal what comes out. So the Earth must achieve equilibrium, and we experience that as warming. Hotter temperatures here on Earth.

[Hannah Chin]

Right. And longer summer heat waves.

[Emily Kwong]

And also humidity, which is going up in some places.

[Hannah Chin]

Right. Because when the humidity is worse, our bodies are less efficient at evaporating sweat. And then if our sweat doesn't evaporate, our systems literally can't cool down.

[Emily Kwong]

Yeah. And when our bodies can't cool down, that is when you put yourself in danger of heat exhaustion or heat stroke or even death. And when we talk about heat proofing our future, the most important thing to think about is that your location, your geographic location will be the biggest factor in determining how you experience extreme heat.

[Hannah Chin]

I mean, Emily, you and I have talked about the urban heat island effect, where buildings and roads and other infrastructure basically trap heat and make these urban areas hotter.

[Emily Kwong]

Yeah.

[Hannah Chin]

This disproportionately affects poorer communities and communities of color, because those areas already tend to have fewer parks and trees.

[Emily Kwong]

Right. So a key adaptation to extreme heat is to green the landscape, especially urban landscapes, by expanding parks and community gardens and installing green roofs.

[Dwayne Stillwell]

Vegetation siphons water from below the land surface and sends it to the atmosphere through transpiration, which is a form of evaporation. And evaporation cools. And so it's a really Effective way of wicking heat away from the surface.

[Emily Kwong]

And there's another adaptation I want to talk about, Hannah. Cooling centers. Cooling centers are air conditioned public or private spaces. They're a real tool in the state of Arizona. Nick Staub is the incident commander for extreme heat response in Maricopa county, where our listener Duane lives. And the reason I wanted to talk to him is because by the department's count, heat related deaths in Maricopa did go down last year. And it is in large part because the county is making an effort to care for those who are most vulnerable.

[Nick Staub]

Those who are at highest risk in our community are those who are unsheltered, those who are, you know, spending their nights out on the street.

[Emily Kwong]

Typically at night, you know, the temperature drops and people's bodies have a chance to recover from the heat exposure during the day. But Nick gets worried when he sees a forecast with a string of high overnight temperatures of nights above 90 degrees Fahrenheit. And people who don't have regular access to shelter aren't the only high risk groups. Other groups include children, older adults, people who are pregnant, people who work outdoors, and many more. Kim McMahon, the public weather services program manager at the national weather service, put it this way. The more susceptible you are, the more exposed you are, the greater your chances of feeling those impacts from heat.

[Hannah Chin]

Starting to get heat rash, starting to.

[Emily Kwong]

Get heat exhaustion before, say, somebody who.

[Hannah Chin]

Works in an air conditioned office building.

[Emily Kwong]

So in response to these heat related deaths, the Maricopa county department of public health decided to expand their heat heat relief network. A whole bunch of organizations came together to keep cooling centers open longer into the evenings, on weekends, holidays. The county also opened up these respite centers, places with blankets where people can lie down and even sleep for a.

[Hannah Chin]

Few hours, right, so that they can rest and they can cool off.

[Nick Staub]

And then we put a big effort into advertising the heat relief network as well as getting consistent street signage printed so that we could put them outside of the center so people could see those signs and know it was a cooling center.

[Hannah Chin]

Hmm. So did it work? Like, has it been successful?

[Emily Kwong]

It has. At least in 2024, the number of heat related deaths that they counted went.

[Nick Staub]

Down, but we still had over 600 heat related deaths in 2024. So while we are encouraged by the reversal of the trajectory, there is still a lot of work to be done.

[Emily Kwong]

And of course, as with all public health data, undercounts are always a possibility. Summers in Arizona will only get hotter. And not everyone may want to stay.

[Hannah Chin]

Right. I Mean, everybody is different. Every community is different. You mentioned that several European countries have these heat early warning systems. Yeah, and I'm pretty sure we have something similar in the US Because I know I have gotten texts about like, extreme heat.

[Emily Kwong]

Yes, let's end on this. Early warning systems. So in the US we have a system of weather emergency alerts which can be sent directly to your device as a text. Text message or a notification about a flash flood or a thunderstorm or an extreme heat advisory. And one of the main participants in the system is the National Weather Service.

[Hannah Chin]

Huh. Okay, so how does the National Weather Service think about heat? Like, what are they doing to address it?

[Emily Kwong]

Well, the National Weather Service is responsible for all weather forecasting in the U.S. they do science, and one of the tools they use is the heat index. The heat index is a measure of how hot it feels to the human body when relative humidity is combined with air temperature.

[Nick Staub]

Oh.

[Hannah Chin]

That's why, like, if I scroll down on the weather app on my phone, like when I look at the daily forecast and then I swipe up, there's this feels like temperature and it's sometimes a little bit different.

[Emily Kwong]

Yeah, it's like the heat vibe, you know, and it's. It often feels more accurate because humidity is factored in. So that's the forecasting system. But then you also need a warning system. Right? Right. Over the years, each local forecast office of the National Weather Service has developed a unique set of thresholds for when in that community the outdoor conditions trigger a heat watch or warning or advisory. But it's not a foolproof measure. Nick pointed out to me for assessing your personal risk, we see a significant.

[Nick Staub]

Number of heat related deaths on days that are not an extreme heat warning. Which is why our messaging to the public is you need to plan all summer long.

[Emily Kwong]

The heat index values are, are calibrated for shady locations, which means this heat early warning system does not fully account for people being in direct sunlight. And that can be 15 degrees hotter than in the shade.

[Hannah Chin]

Wow. Okay, so basically, don't wait for that text message to change your outdoor plans. I mean, under these circumstances, I guess I'm wondering what can people realistically do about it? Like if they know a heat wave is coming and they're worried?

[Emily Kwong]

Yeah. So assess, you know, where you live, your individual heat tolerance. But if you know it's about to get really hot, you have to take precautions. For Nick in Arizona, it's about treating all Maricopa county summers like a heat watch is constantly in effect.

[Nick Staub]

Plan your outdoor activities wisely. Don't be outside during the heat of.

[Emily Kwong]

The day, install dark curtains, take cold showers, check in on friends and family and neighbors to make sure they're doing okay while the heat wave is doing its thing. It's all good advice, but I was not totally satisfied with some of these answers. Huh. Wait, how come because individuals and local governments can only do so much, we cannot cold shower our way out of this?

[Hannah Chin]

Okay.

[Emily Kwong]

Justin says ultimately it is fossil fuel emissions that are the root of the problem.

[Dwayne Stillwell]

Mitigating our greenhouse gas emissions is going to be the clearest way to prevent additional warming and extreme heat risks, and we have the tools to do it. We have had policies in place to help achieve it, and neglecting the problem is not going to make it go away.

[Emily Kwong]

It's only going to make the world hotter.

[Hannah Chin]

Emily Kwong, thank you so much for bringing us this reporting.

[Emily Kwong]

You're welcome, Hannah. Thank you Duane, for the great question. Shortwavers if you have a question about changes in your environment, email it to [e-mail] and we'll consider it for a future Nature Quest episode. The series comes out the last Tuesday of every month. Special thanks also to the National Weather Service and to Alejandra Burunda and Julia Simon on NPR's Climate Desk.

[Hannah Chin]

This episode was produced by Hannah Chin. That's me. And Rachel Carlson. It was edited by our showrunner, Rebecca Ramirez. Tyler Jones Check the facts. Jimmy Keeley was the audio engineer, Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Hannah Chen.

[Emily Kwong]

And I'm Emily Kwong. Thanks for listening to Shore Wave. Foreign.

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